FZ200 Diffraction Limit - Panasonic Tech Service

Started Aug 27, 2013 | Discussions thread
Detail Man
Detail Man Forum Pro • Posts: 16,788
Re: Are 2 pixels per line-pair enough ?

Stephen Barrett wrote:

Something is wrong with my last post. The test result of 1.3 pixels per line-pair for the FZ50 doesn't make sense. Either the test is too good or I blundered in my calculation. Too bad i have to go out now. It's going to drive me nuts.

It's heartening to see such rampant and unabashed "nerdism" (a good thing in my book) at play.

Fear not, by the end of today I plan to provide you with the spreadsheet tools to (directly) surf in the spatial frequency domain. With all knowledge comes some suffering, but also deeper insights.

You will find that arbitrary MTF "lower thresholds" are only metaphors for situations where (depending on the Signal/Noise Ratio) image-data information may potentially not be adequately "recoverable" in processing. The MTF of an Airy disk diameter of 2.44 * Wavelength * F-Ratio happens to be arouns 8.9 %. That is only one of the several factors that multipy to generate the net composite system spatial frequency (MTF) response.

Two photosites cannot be enough - simply because of the spatial frequency spectrum of periodic line-pairs (a "square wave" containing higher order harmonics as well as a fundamental spatial frequency), the Shannon-Nyquist sampling theorem, and the random-phase of aligning projected periodic line-pairs onto an image-sensors array of photosite locations. It's that simple.

DM ...

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